We’ve all heard Boston is threatened by rising seas associated with climate change.
New research shows the city is facing another phenomenon that is expected to make flooding even worse.
The city is actually sinking.
“To hear that Boston is sinking, it actually puts a pit in my stomach,” said Boston City Councilor Gabriela Coletta Zapata, who represents East Boston, Charlestown, and the North End.
“So, if we have a declining surface, and we have relative sea level rise, that in turn creates more frequent flooding events, more severe flooding events,” said James Heiss, Ph.D., an associate professor of hydrogeology at the University of Massachusetts-Lowell.
This sinking phenomenon is called subsidence.
It is occurring in other cities like San Francisco, New Orleans, and Miami.
Heiss said that even though the rate of depression is measured in millimeters, the negative effect is real.
“In New England, in Massachusetts, subsidence contributes about 15% of sea level rise.”
One contributing factor in cities like Boston is the sheer weight of development caused by heavy skyscrapers.
Another reason particular to this region is traced back to the Ice Age.
Heiss explained that the weight of glaciers forced the crust of the earth downward while along the perimeter of a glacier, the land would actually rise up.
“There was sort of this seesaw effect.”
Heiss added that now the land surface where the glaciers once sat is rising and the area along the perimeter is now subsiding.
Sinking is about the last thing Boston needs.
According to www.sealevelrise.org, the sea level has risen 8 inches since 1950 in the Boston area. It’s expected to swell another 6 inches over the next 15 years.
“In some areas, it can lead to structural issues with building foundations,” Heiss said.
That’s why subsidence poses a threat to places like Boston’s Back Bay which was built up with fill and expanded back in the 1800s.
Councilor Coletta Zapata said her district in “particular will be hit first and worst.”
What concerns her most now is the sunny day flooding that happens during King Tides.
She’s worried about when the next big storm hits Boston. “The question that for me now remains is a matter of when, not if”.
The councilor told Boston 25 News this issue of subsidence is on the minds of city officials as they discuss climate change initiatives.
“When I hear that scientists are saying that Boston is sinking, I think about the real-world implications it has on the people that live in my district. . . these are people’s homes. So, what does it mean when thousands of people have to be displaced or businesses have to move because the flooding just becomes so overwhelming?”
Coleta Zapata said the biggest challenge for Boston right now is figuring out how to pay to fortify the city’s 47-mile-long coastline.
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